First complete mitochondrial genomes of Ototretinae (Coleoptera, Lampyridae) with evolutionary insights into the gene rearrangement.

The subfamily Ototretinae represents an important and unusual lineage of fireflies. Here, we sequenced and annotated three mitogenomes for this subfamily, with two Stenocladius species and one Drilaster species as representatives. The mitogenome of Stenocladius exhibits a rearranged gene order between trnC and trnW caused by transposition, which is a novel finding in Lampyridae. Meanwhile, a long intergenic space (241 to 376 bp) exists between the two rearranged genes, and some remnants (23 bp) of trnW are present within this non-coding region. Moreover, phylogenetic analyses did not recover the monophyly of Ototretinae, in which Drilaster is shown at a basal lineage in Lampyridae, but Stenocladius seems more related to Luciolinae. Therefore, the gene rearrangement in Stenocladius is presumed to result from independent evolutionary events, suggesting that this genus should be placed in a separate lineage. Nevertheless, more representative mitogenomes from different groups are required to verify the present results.